A turbocharger center housing rotating assembly (CHRA) can include a turbine wheel and a compressor wheel attached to a shaft rotatably supported by a bearing assembly located in a bore of a center housing. A bearing assembly or bearing cartridge can include an outer race and an inner race, configured to receive a shaft, where the outer race and the inner race are separated by rolling elements such as ball bearings.
In various CHRAs, a so-called “locating mechanism” restricts movement of a bearing assembly in the bore of the center housing. A locating mechanism may rely on radial insertion of a locating pin in an opening of an outer race of a bearing assembly. Such a mechanism restricts radial and/or axial movement of the bearing assembly and rotation of the outer race yet allows the inner race to spin freely. Additionally, such a mechanism allows for some radial movement of a bearing assembly, usually within defined clearances that fill with lubricant during operation to form a “squeeze film” that acts to damp vibration and noise. In such a CHRA, the degrees of radial and axial freedom may be chosen to be of particular magnitude or magnitudes depending on various goals.
Various issues can arise with locating mechanisms that rely on a radial locating pin to locate a bearing assembly. For example, during operation of a turbocharger, significant axial loads can be generated that thrust the turbocharger shaft and associated components toward the compressor end or toward the turbine end of the turbocharger CHRA, which, in turn, can be transferred from the bearing assembly to the radial locating pin. Another issue pertains to axial stack-up of components (e.g., how well do the components of a CHRA stack and how does this stacking affect operation and wear).